The present invention relates to snack chips, particularly uniformly-shaped tortilla-type chips, having raised surface features.
Tortilla chips are particularly popular consumer snack products. Tortilla chips are traditionally made from whole kernel corn that has been cooked in a hot lime solution for about 5 to about 50 minutes, then steeped overnight. The cooking-steeping process softens the outer hull and partially gelatinizes the starch in the endosperm of the corn. This cooked-steeped corn, called xe2x80x9cnixtarnal,xe2x80x9d is then washed to remove the outer hull and ground to form a plastic dough, known as xe2x80x9cmasa,xe2x80x9d that contains about 50% moisture. The freshly-ground masa is sheeted, cut into snack pieces, and baked for about 15 to about 30 seconds at a temperature of from about 575xc2x0 F. to about 600xc2x0 F. (302xc2x0 C. to 316xc2x0 C.) to reduce the moisture content to from about 20% to about 35%. The baked snack pieces are then fried in hot oil to form tortilla chips having a moisture content of less than about 3%. See, e.g., U.S. Pat. No. 905,559 to Anderson et al., U.S. Pat. No. 3,690,895 to Amadon et al., and xe2x80x9cCorn: Chemistry and Technology,xe2x80x9d American Association of Cereal Chemists, Stanley A. Watson, et. al., Ed., pp. 410-420 (1987).
Tortilla chips can also be made from dried masa flour. In typical processes for making such dried masa flour, such as those described in U.S. Pat. No. 4,344,366 to Garza, U.S. Pat. No. 2,704,257 to Diez De Sollano et al., and U.S. Pat. No. 3,369,908 to Gonzales et al., the lime-treated corn is ground and dehydrated to a stable form. The dried masa flour can be later rehydrated with water to form a masa dough that is then used to produce tortilla chips in the traditional manner.
The finished, fried tortilla chips are characterized by randomly dispersed, raised surface features such as bubbles and blisters. The tortilla chips have a crispy, crunchy texture and a distinctive flavor characteristic of lime-treated corn products. The individual dough pieces assume random formations during frying, thus producing chips of non-uniform shape and curvature.
The finished tortilla chips are generally packaged by placing them into a bag or a large-volume canister in a randomly packed manner. Such random packing leads to a packaged product with low bulk-density. Packages with low bulk-density are essentially packages wherein the volume capacity of the package is much greater than the absolute volume of the snacks contained inside. In other words, the package contains a much lower net weight of snack pieces than could be held by the volume capacity of the package.
These large volume packages permit the randomly packed chips to settle along the bottom of the bag or can, creating a large outage in the package (i.e., the total volume of the package minus absolute volume of the product held within the package). This outage not only permits the presence of a significant amount of oxygen and moisture inside the package, thus increasing the opportunity for the chips to become rancid and stale, but also creates a lower value perception for the consumer. Furthermore, this type of package provides little protection from handling and shipping loads imposed upon the fragile chips, and thus it is quite common for consumers to find a considerable number of broken chips within the bag.
Tortilla chips and chip dips, or xe2x80x9csalsas,xe2x80x9d are a very popular snack combination. However, because of the randomly shaped nature of the chips, consuming tortilla chips that have been dipped in salsa can create a very messy eating experience for consumers. Because of the randomly shaped nature of the chips, the chips do not adequately hold or contain the dip after it has been put on the chip; this is especially true for the fluid portion of the dip. Because most tortilla chips do not have a defined dip containment region or xe2x80x9cwellxe2x80x9d capable of holding fluid dips on the chip, the dip or a portion thereof can readily flow off the surface of the chip, often landing undesirably on clothing or household furnishings.
Accordingly, it would be desirable to provide a uniformly shaped tortilla chip with a defined containment area for dip. It would also be desirable to provide such a tortilla chip which is capable of being stacked one upon the other to form a high-density grouped array and packaged into high-density containers, such as canisters, to reduce breakage. It would also be desirable to provide such a chip that can be produced using a simplified, one-step cooking process rather than the combined baking and frying steps employed in traditional tortilla chip manufacture.
Many problems are encountered when trying to make such a tortilla chip. The stacking of uniformly-shaped tortilla chips upon each other, such as in a nested arrangement, can lead to the abrasion and ultimate breakage of the surface features (i.e. bubbles and blisters) which are characteristic of tortilla chips. This breakage leads to an undesirable surface appearance and to the loss of the chip""s crunchy texture.
To date, there has been an absence from the market of nested tortilla style chips. Tortilla style chips can be characterized by a plethora of bubble like surface features breaking through the base plain of the chips. The bubbles are a necessary part of the tortilla chip, providing a dichotomous texture experience with varying levels of crispness with each bite. The presence of bubbles in a chip made with corn is a key visual signal to the consumer of this desirable texture benefit. Corn chip products without surface bubble structures tend to have a dense or glassy texture that is less preferred by some consumers versus the light, crispy tortilla chip texture as evidenced by the more rapid growth of the tortilla chip market segment.
A potential reason for the absence of nested tortilla style chips is the inherent tradeoff that can exist between placing the fragile bubble surface features within intimate contact of adjacent chips. With nested arrangements, there is even a higher probability of direct contact between the lower surface of one chip and the upper surface of an adjacent chip. The direct contact can lead to abrasion and breakage of the surface bubbles leading to a negative visual appearance and loss of texture dichotomy. Additionally, the formulations and methods for making nested chips can directly impact the formation and strength of surface bubbles. There are several problems that make it difficult to deliver a high quality, nested tortilla style chip meeting the end consumer""s expectations for this product category.
The moisture loss history of the dough piece during frying typically follows traditional drying theory, wherein there is an initial constant rate period of rapid moisture release that is not limited by diffusion through the dough. The vast majority of moisture loss occurs very early within frying when the dough first contacts the hot oil. The quality of the final product texture is highly dependent upon the early moisture loss history. The final product can assume a variety of three dimensional shapes due to the convective forces of the oil contacting the product surface during cooking.
Surface bubbles form due to a balance of simultaneous forces that include a rapid evolution of steam volume coupled with limited interstitial channels to transport the steam and localized gelatinization of the dough piece surface. A rapid evolution of steam from the constant rate period of moisture loss during frying momentarily overwhelms the diffusion capacity of the dough causing the steam to remain briefly trapped. When the steam comes in contact with a gelatinized dough region of sufficient tensile strength, a surface bubble is formed. The bubble formation is stopped when the steam eventually escapes through another surface location.
The first requirement for nested tortilla chips is that each chip should be substantially uniform in size and shape so that the chips can be fit one within another with minimal spacing between the chips. Making snack pieces of uniform size and shape can be accomplished by constraining and cooking a dough piece of a specified thickness to a pre-determined size and shape between a pair of arcuate molds also of a specified size and shape. An apparatus such as the one described in U.S. Pat. No. 3,626,466 issued to Liepa on Dec. 7, 1971, can be used.
The dough must have sufficient strength to be to be formed into the shapes on the constrained frying molds, but not be so inflexible that the dough piece would crack upon bending. Removing too much water, or removal at too high of a rate during the baking step, could render a tortilla dough inflexible. Conversely, some amount of increased dough viscosity is needed to provide the strength necessary to form a defined shape. A critical level of dough viscosity is also required to enable the surface bubble expansion that occurs during frying, otherwise the bubbles would break or collapse quickly after formation. It would be ideal to have a dough composition that has both sufficient strength for bubble and shape formation and the desired flexibility, without the need for baking prior to frying. Such a dough would greatly simplify the process by eliminating a costly and complex unit operation.
A second requirement for a tortilla style chip is the presence of surface bubbles via a random expansion of the dough which is highly dependent upon the rapid release of moisture from the dough as it is cooked. However, the method of making nested snack pieces in a manner leading to low variability in size and shape of the final cooked snack pieces can lead to a lessening of heat and mass transfer rates to the constrained dough piece that are detrimental to the appearance and texture of the final product. Specifically, the molds used to constrain the dough delay the transfer of heat to the dough piece. The frying oil has a delayed contact with the dough after it first passes through or around the cooking molds. More significantly, the molds limit the rate of moisture transport away from the dough surface. As the dough heats up to reach the boiling point of water, evaporation of the water within the dough begins where the steam makes its way towards the surface of the dough piece. In typical tortilla chip making where the dough pieces are randomly free fried in the oil, the steam would quickly escape away from the chip surface. However, with constrained frying molds, resistance to the steam movement exists. The steam becomes trapped, forming a boundary layer between the dough and molds. The steam acts as an insulator preventing the hotter frying oil from contacting the dough surface, thus generating further heat and mass transport limitations. The limitations of the steam movement are further exaggerated at the bottom of the dough piece. The natural tendency for steam bubbles to rise to the surface via buoyancy forces is inhibited. The resistance created by the lower mold forces steam bubble to travel transversely along the dough surface until reaching an escape point where it can break free of the mold or dough piece and ascend vertically through the frying oil. In traditional free frying of tortilla chips, the dough piece is continually moving at random angles vs. the oil, which prevents steam from accumulating along the product surfaces.
The impact to the product of the reduced heat and mass transport that can accompany constrained frying is reduced bubble formation, leading to a final product with dense, undercooked sections containing starch with a gummy texture due to over hydration with water during cooking. Increased starch gelatinization occurs in the presence of extreme heat such as frying temperatures and water that can be readily absorbed by the starch at elevated temperatures. During traditional random free frying of tortilla chips, the moisture rapidly leaves the snack piece, thus quickly eliminating one of the conditions needed for large levels of gelatinization to occur.
Several types of texture problems can occur with constrained fried tortilla chips. A puffed chip structure can occur as a result of increased levels of gelatinized starch films forming across a large percentage of the surface of the dough, creating a barrier retaining the steam within the dough. The resulting internal pressure causes the dough piece to expand within the gap between the upper and lower mold halves. The final product can be universally expanded having a pillow like appearance with distinct surface bubbles ranging from few to none. It is possible for this puffed structure to collapse upon itself with certain dough compositions or cooling conditions post frying which leads to a further worsening of the texture.
If the heat and mass transport are more severely constrained, little to no expansion of the dough may occur. A slow evaporation of moisture and release of steam bubbles can result. Instead of a rapid constant rate period of moisture loss, the moisture evaporates slowly and at a more even rate. While the target final moisture of the product may have been met, the path to get there would be very different. Random bubble formation is absent due to a lack of a vigorous release of steam through the interstices of the dough which would have lead to small localized pockets of steam leaving the surface leaving bubbles behind in their wake. A dense, flat final chip results.
Bubbles resulting in the final product can be too weak to survive the abrasive forces that would be experienced in a nested arrangement. The dough can be spread into a thinner, weaker surface layer by the pressure of trapped steam. It has also been observed that bubbles form on each side of the chip due to increased mass transport resistance, one above the other, creating a localized region of increased thickness that is more likely to get pinched by adjacent chips by creating a common pressure point.
Accordingly, it would be desirable to provide a chip having surface features that do not break when the chips are stacked upon each other, yet is not too hard.
These and other objects of the present invention will become apparent from the following disclosure.
The present invention provides uniformly shaped, tortilla type snack chips. The chips can be made from a dough compositing comprising:
a. from about 50% to about 80% of a blend comprising:
i. at least about 50% of a precooked starch-based material;
ii. at least about 0.5% pregelatinized starch, wherein said pregelatined starch is at least about 50% pregelatinized; and
b. from about 30% to about 60% total water.
Preferably, the snack chips have raised surface features comprising from about 12% to about 40% large surface features; from about 20% to about 40% medium surface features; and from about 25% to about 60% small surface features. In one embodiment, the average thickness of the snack chip is from about 1 mm to about 3 mm; the average thickness of raised surface features is from about 2.3 mm to about 3.2 mm; the maximum thickness of the chip is less than about 5.5 mm; and the coefficient of variation of the chip thickness is greater than about 15%.
These and other objects of the present invention will become apparent from the disclosure and claims as set forth below.